Attachment for spark plugs



S. DONALDSUN.

ATTACHMENT FOR SPARK PLUGS.

APPLICATION FILED AFR. I, I92l.

Patented Sept. 19, 1522;

2 SHEETS-SHEET I.

T, i |IIIII III' l 'aarz analdson.

@thune-11 5.

DQNALUSUN.'

" ATTACHMENT FOR SPARK lPLUGS.

APPLICATIQN FILED APR. 1v, 1921.

Patented sept. "19, 1922.

A2 SHEETS-SHEET 2.

25 4 is an elevation,'partly in section showing Patented Sept. 19, 1922.

s'rgAar DONALDSON, or cARivneaE,y `1 ENNSYIALANIA.

Ar'rAoHivriiN'rroit SPARK FLUGS.'

Application led April 1,

To all 'whom tima-y concern l Be it known that l, lSTUART DONALDSON, a citizen of the United States, vresiding at Carnegie, inv the county of Allegheny and tate of Pennsylvania, have invented certainl new and useful Improvements in Attachments for Spark Plugs, of which the following is a specification.

rlhis device which is vthe subject matter ofthe present application for patent is a novel and improved attachment for spark plugs having for its object to enable the plug to be tested for determining whether it is functioning properly, and so constructed and arranged that it may also be set to produce an auxiliary spark gap and thus act as a spark intensifier.

in order that the invention-may be better understood, reference is had to the accontipanying drawing'forniing a part of this specication, 'and in said drawing,

Fig. 1 is an elevation showing one embodiment of the invention; Fig. 2is a central vertical section thereof; Fig.v 3 is ak horizontal section on the line 3-'3 ofFig. 1;.Fig.

another embodiment of the invention, and

` Figs. 5 and 6 are vertical sectional views showing further modifications. j

InFigs. 1 and 2, theinvention is shown as forming a part of anV ordinary spark plug,

whereas Fig. 4 shows 4the device as a unit separate from the spark plug and detachably connected thereto.V

The spark yplug shown in Figs. 1 rand 2 consists of the usual' porcelain' body' ,carried by the metallic base shell 6 having a reduced threaded end 7 to screw Vinto the engine cylinder, and formedr with 'a stuffing box which receives a gland 8. Theporcelain body 5 carries the main central terminal ro'd 9, the same projecting from the cylinder endjof the plugl and` being here opposite the usual groundedside electrode 10 carried by the shellv6. j These partsA are all Vconstructed and arranged in the usual manner, and hencer 4a detailed description thereofv is net necessary. The projecting cylinderv end of the body `5 has an external annular groove 11 to prevent or reduce' the tendency of carboncollecting in a solid surface on such Vprojecting part.

The rod 9 projects from the outer end of the` body 5, and over this endvof said body is mounted a cylindrical housing "12 of suitable insulating "material, having its inner i921. serial No. 457,783.

end open and externally threaded for ati tachment tothe plug by being screwed into the outerl end of the gland nut 8', the latter" l having its bore enlarged suiiiciently fand screw-threaded to receive the threaded inner.

end of the housing as shown in Fig. 2.k The s proj ect-` into Ithe housing. vThis cap carries aterminal'rod 15 which is in alinement with therod 9, and when in contact with the latter it forms va continuation thereof, Whereas When spaced a suitable distance there is produced an auxiliary spark gap between the Opposite ends of the rods.' l i The outer end ofthe rod15 projects from the back of the cap 13, and it is here'fitted with a lock nut 16 and a clamping nut 17 for attaclnnent lof the current wire. The nut 16 seats in a Arecess 18 `inthe back of the cap, and in the inner -endof the part 14 of the cap is a recess 19 in which seats a cross pin 2O carried by and projectingl sidewise from the rod`15'.A lt will'ftherefore be seen `that the cap 13 andthe rod 15 are rigidly connected vwhen the nut,16 yis screwed` A'dovvnl to draw ythe cross pin-20 and the inner end of the cap' together. j l

That portion of the cap 13 which seats on the outer'edge ofthe housing 12 lhas Aa number of depending lugsv21,l andthe edge of the housing has corresponding recesses 22*l v Two. diametrically opposite` recessesy are,

made deeper than'the othertwoand the lugs larek made correspondingly longer and, The arrangement? is'. such that` shorter.

when .the long lugs are" seated Vin the shal` low recesses, as shown in Figs.l 1j and 2, the f rods'9 and 15 aresep'arated and the auxi'l-` iaryj'sparky gapjis obtained, Whereas when the cap is rotated-so `that the short lugs are seated vin the shallow recesses, and the [long 5 l' lugs in theV deep recesses, the cap 13 is moved inwardly'a distance to bring the inner end of the vrod 15 in contact' with `the outer. endJVA ofthe rod 9. -The cap 13 is in'this manner adjustable inthe direction of the length of the housing 'V12 to 'carrythe rod l15 into and out of contact with the rod 9. In order that thespark at the auxiliary gap may beq obopenings 23.

served, the Iside'of the housing 1 2 has sight j s v When the cap 13 is adjusted to bring the rods 9 and 15 together, the latter form a continuous conductor for the passage of the electric current, and the spark plug noiv functions in the same -manner as any ordinary single-gap spark plug. lf it is desired to test the plug, the cap 13 is moved back to separate the rods 9 and 15 as hereinbetore described, and it the plug is proper y vfunctioning, ra spark Will be observed at the auxiliary gap between the rods, the spark being visible through the openings 23. It the device is to iunction as a spark intensiiier, the rods 9 and 15 may be lett separated toY maintain the auxiliary gap.

ln order to-tirmly lock the cap 13 in adjusted position, there is fitted around the inner end of the rod 15 a coiled spring 24 seating at one end against an abutment 25 on saidrod, and at its other end against a yWasher 26 loose on the rod, said Washer bearing on a disk 27 lWhich latter seats against a shoulder 23 on the inside of the housing 12. The pressure Aot the spring 24 against the abutment 25 draws the rod 15 inwardly, and as said rod is fastened to the cap 13, the latter is held firmly seated c on the housing 12 with its lugs 21 in the recesses 22, so thatthe cap cannot be jarred loose to disturb the position of the rod 15 with respect to the rod, 9. The rod 15 is advanced or retracted by a slight outward lpull on the cap 13 and a quarter turn to lunit separate from the .spark plug.

seat Athe lugs 21 in the proper recesses 2 2 required tor the desired position of the rod i5. f j

Fig. Il, shoivsthe device as a complete In this embodiment ot the invention, the housing 12 isclosed at its inner end and vhere fitted With a central terminal stud 29 ,which has a threaded laperture on the outside ot the housing` end so that it may be screwed on the projecting threaded. end of the center electrode or vterminal rod 9. rThe stud 29 extends slightlyinto the housing so as to be opposite the inner end oi the rod 15. l/Vhen the rod 15 is spaced from the stud 29, the auxiliary spark gap is obtained, Whereas When the rod is brought into contact with the stud, a continuous conductor for. the passage of "thef electric current is had. f

The disk 27 is held in place in the housing .12 by being snapped into an internal annular groove 30. 1

The last described device can be readily attached to vany standard spark plug, and it aifords a simple and eiiicient means for testing the plug and also tor converting the .same into a double-gap plug.

Figs. 5 and Gillustrate a diiierent method of attaching theY terminal rod 1 5 to the housing cap 13. lThe cross pin 2O is left ott", and a nut 31 is built into the cap 13,

the upper end of the rod 15 being threaded so that it'may be screwed into the nut. A lock nut 32 is mounted on the threaded portion of the rod, and When it is screwed down tight against the nut 31, the cap 13 and the rod 15 are rigidly connected. rlhis construction also permits any necessary longitudinal adjustmentof the rod 15.

Fig. 6 also illustrates a modification'of the device shown in Fig. 4C. Instead of stud 29 shown in Fig. 4t, the inner end of the housing 12 is iitted With a metallic cap 33, the saine kbeing threaded to screvv into the housing. That end of the cap which extends into the housing is made pointed and located opposite the inner end of the rod 15 for the saine purpose as the stud 29.

The cap 33 also has a threaded aperture of the housing for attaching the same to a spark plug, lugs on the under side of the cap opposite the housing end, said housin end having recesses lto seat said lugs, said recesses and lug varying in depth and length to gage the extent o1 the sliding movement of the cap relative to the housing, an electrode rod carried by the cap and extending into in the same manner as the stud 29 of the housing, and means Jfor connecting' a current conductor to the electrode rod, saidk rod being adjustable by the sliding movement of the cap to establish an electric connection with the main terminal rod of the spark plug in one position of the cap, and to form an auxiliary spark gap in another position of the cap.

2. An attachment for spark plugs, comprising a housing having a sight opening, a cap rotatably and slidably fitted to one end of the housing, means at the other end of the housing for attaching the same to a spark plug, lugs on the under side of the cap opposite the housing end, said housing end having recesses to seat said lugs, said recesses and lugs varying in depth and length to gage the extent of the sliding movement ofthe cap relative to the housing, an electrode rodv carried by the cap and extending into the housing, means for connecting a current conductor to the electrode rod, said rod being adjustable by the sliding movement of the cap to establish an electric connectionpWith the main terminal rod of the spark plug in one position of the cap, and to :term an auxiliary spark gap in another position of the cap, and a spring coiled around the electrode rod for holding the cap seated, the rod having an abutment against Which one end'of the spring bears, and the housing containing an abutment Jifor the other end of the spring.

3. An attachment for spark plugs, comprising a supporting member having recesses at one end, means at the other end of said member Jfor attaching the same to a spark plug, an electrode rod, and a slidable and rotatable support for the electrode rod seating on the recessed end of the supporting member, and provided With lugs to seat in the recesses, said lugs and recesses varying in length and depth to gage the extent of the sliding movement of the electrode rod support in a direction to advance and to retract the electrode rod relative to the main terminal rod of the spark plug.

4. An attachment for spark plugs, comprising a supporting .member having recesses at one end, means at the other end of said member for attaching the same to a spark plug, an electric rod, a slidable and rotatable support for the electrode rod seating on the recessed end of the supporting member, and provided With lugs to seat in the recesses, said lugs and recesses varying in length and depth to gage the extent of the sliding movement of the electrode rod support in a direction to advance and to retract the electrode rodrelative to the main terminal rod of the spark plug, and a spring coiled around the electrode rod for holding the support thereof seated, said rod having an abutment against Which one end of the spring bears, and the supporting member carrying an abutment for the other end of the spring.

5. An attachment for spark plugs, comprising a housing having a sight opening, a cap rotatably and slidably itted to one end of the housing, means at the other end of the housing for attaching the same to a spark plug, lugs on the under side of the cap opposite the housing end, said housing end having recesses to seat said lugs, said recesses and lugs varying in depth and length to gage the extent of the sliding movement of lthe cap relative to the housing, an electrode rod carried by the cap and extending into the housing, said rod being longitudinally adjustable relative to the cap, and means for connecting a current conductor to the electrode rod, said rod being adjustable by the sliding movement of the cap to establish an electric connection With the main terminal rod of the spark plug in one position of the cap, and to form an auxiliary spark gap in another position of the cap.

In testimony whereof l alix my signature.

STUART DONALDSON. 

